A poor diet and a lack of exercise is causing obesity in children

Professor Julian Peto believes teachers should include a child's body mass index in their annual reports on a pupil.

He thinks this should be sent home to parents along with a reminder of the long term health implications of obesity.

He told a health select committee in June that obesity can reduce life expectancy by seven years.

Good habits

Obesity is now as big a killer as smoking but while the number of people smoking is on the decline, levels of obesity are rising.

He believes the best way to tackle the problem is to start dealing with children's obesity and starting good eating habits at a young age.

Many parents do not want to face up to the fact that their child is overweight, he said.

But a teacher can be objective about a child's weight.

The body mass index is a calculation based on comparing a person's weight with their body height. It applies equally to boys and girls.